Applications for high intensity, high efficiency narrow beams are prevalent through the lighting industry. Certain industries, for instance the entertainment, architectural or theater industries, have applications for specialized lighting which can benefit from an apparatus or system which is able to collimate and control the direction at which the light is projected. In addition, there is a need to “throw” or project a selected color for a relatively long distance while maintaining an acceptable level of illumination and color uniformity. A long throw distance requires a narrow beam at a high intensity, while minimizing the intensity dispersion.
A directed light beam is light emitted in a preferred direction, and can be characterized by beam angle and dispersion. Beam width refers to the full-beam dispersion angle at which the off-axis luminous intensity of the light is one-half of the maximum on-axis luminous intensity (measured in candela), and field width refers to the full-angle at which the off-axis luminous intensity of the light has fallen to 10% of the on-axis luminous intensity. Dispersion is a measure of the distribution of the luminous intensity over the beam angle. The throw distance is increased when the emitted light is concentrated into a small beam angle with a small dispersion.
Conventional LED arrays produce light emissions having a relatively wide Lambertian beam angle of, e.g., 120°. The conventional LED arrays can be coupled with primary optics, thereby capable of forming, for example, an LED light engine in a 1.5×1.5 inch package and producing a light beam having an intensity of 1,000 lumens over a still wide beam angle of 60°, such as the Lamina Lighting Titan™, suitable for some residential, stage, architectural, and commercial lighting applications. Such light engines typically include multiple emitters and cavities to produce a light beam having an acceptable intensity, however this increases the apparent source size to be much larger than the apparent source size from a single emitter light engine, thereby making it more difficult to collimate the light into a beam having a low level of intensity dispersion.
Conventional collimation solutions which are tall (e.g., ≧5″) or wide (e.g., ≧6″) are too costly to manufacture, ship, and install when the light source itself is already two to three times the cost of energy-inefficient incandescent and halogen sources that it replaces. A compact, low-cost collimation design is preferable for applications where space or cost considerations dominate. Therefore, a need exists to provide a compact, low-cost optics assembly which can optimize the collimation and throw distance of a light beam produced by a light engine.